1. Field of the Invention
The present invention relates to server management programs, server management methods, and server management apparatuses for managing an application operating on a server computer, and particularly to a server management program, a server management method, and a server management apparatus for grouping and managing a plurality of server computers.
2. Description of the Related Art
When a service is provided to a client, a plurality of server computers can perform distributed processing. In this processing, a load balancer assigns a request from the client to one of the server computers.
In the following description, a function name followed by “server” means a function for providing a service by means of application software operating on a computer. A “server computer” means a computer which executes application software for providing a service.
During system operation, the amount of requested service processing may get close to the limitation of system throughput. In that case, the throughput can be enhanced by adding a server computer to a group of server computers for providing a service (server group), so that the amount of processing will not exceed the system throughput.
If the server computer is added to the server group in response to an operation input from the user, the addition of the server computer may not keep up with an increase in processing load. So, a system for monitoring a service request to a server cluster has been proposed. The system adds a standby server computer provided in advance to the server cluster when a demand for the service exceeds the upper limit (refer to Japanese Unexamined Patent Application Publication No. 2002-163241 (See paragraphs [0028] and [0029]).
A standby server computer can be automatically added to a server group if the configuration of the standby server computer is set up in advance. If the standby server computer can be prepared for a special service, the system as described in patent document 1 is possible.
In a system for providing a plurality of services, preparing a standby server computer for each service is a waste of resources. So, another idea is to provide a common standby server computer for a plurality of services and to add the server computer to a server group for providing a service when the load of the service becomes excessively large. When the target server group is determined, a server application for the server group must be installed on the server computer.
Because the application and the like must be arranged and set up for the standby server computer after the addition to the server group is determined, it would take a long time until the actual operation can start. In a multilayer server system in which a service is provided by a plurality of server applications working in cooperation with one another (such as a service provided by a web server and an application server operating at the request of the web server), a configuration that includes information on other server computers related to the added server computer must be set up. Accordingly, the configuration cannot be set up in advance in a system in which a server computer would be dynamically added to or deleted from the target server group.